What is the name/URL of this app? It's the GURPS character sheet: http://gurpscharactersheet.com/ I have a github repo for my WIP AUR package: https://github.com/silverhammermba/gcs
If building on a box where multiple JVM can be installed: build scripts for Java apps usually provide a "--with-jdk=<PATH>" or "--java-home=<PATH>" (or similar) to force the JVM to use to build. If true for the app you are trying to build then you could use path "/usr/lib/jvm/java-8-openjdk/" Yeah, my primary concern here is multi-JVM boxes. If only Java 8 is installed, there's no issue. The build system is Apache Ant, and I can change the JVM it uses by setting JAVA_HOME for makepkg, but even then I can't assume that Java 8 is java-8-openjdk. For example jre from the AUR also provides java-runtime=8.
I feel like the archlinux-java script should be able to get/set the default Java **per version**. That would make it much easier to handle all this.